If air superiority (which is what is required) has already been established, then the GV attack is pointless. Jabos would be more effective, since they can plaster the town and base, and then imediatly start achieving air superiority.
If we want to have the game so realisitc that air superiority is required to be succesfull, then we should have to put up with limited numbers of fighters per base as well.
Its sort of paper/stone/scissors except we are missing the scissors content from the game play set up.
To capture we need infantry.
Enemy infantry is suppressed by freindly Armoured superiority.
Enemy Armour is suppressed by freindly Air (attack) superiority.
Enemy Air (attack) is suppressed by freindly Air (fighter) superiority.
But in game play our Armoured Superiority does not have to supress enemy infantry (there is no infantry) it just has to stay superior, kill buildings and release a token commando squad.
Both the latter can be done (in game) by air borne forces.
Indeed in game it is not uncommon to just remove armour by destroying a single object (GV Hanger)
Rather than limit air craft my view would be to promote the anti Infantry role to one that can only be carried out by Armour.